V6 Really is that Hard

Sometimes I begin to think that we’ve solved most of the challenges to IPv6 deployment. Then something happens.

This time it was a DAP-1522 access-point. Not a NAT, not a router, just a layer 2 device. A while after deploying the device, I noticed that sometimes mail failed to work. After attempting to debug the problem was that the device wasn’t getting an IPv6 address. The router appeared to be sending out advertizments. Other machines on the same subnet were working fine.

This laptop had associated with the new access point. The default configuration helpfully includes IGMP snooping. The IGMP snooping detected that no one subscribed to any IPv4 multicast group corresponding to the router advertizements and thus didn’t forward them to the wireless link.

We have a long way to go if layer 2 devices sold today are incompatible with v6 in their default configurations.

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